Performance and Return to Sport After
Anterior Cruciate Ligament Reconstruction
in National Hockey League Players
Brandon J. Erickson,* MD, Joshua D. Harris,*† MD, Brian J. Cole,* MD, MBA,
Rachel M. Frank,* MD, Yale A. Fillingham,* MD, Michael B. Ellman,* MD,
Nikhil N. Verma,* MD, and Bernard R. Bach Jr,* MD
Investigation performed at Midwest Orthopaedics at Rush,
Rush University Medical Center, Chicago, Illinois, USA
Background: Anterior cruciate ligament (ACL) rupture is a significant injury in male National Hockey League (NHL) players.
Purpose: To determine (1) the return to sport (RTS) rate in the NHL following ACL reconstruction, (2) performance on RTS, and (3)
the difference in RTS and performance between players who underwent ACL reconstruction and controls.
Study Design: Cohort study; Level of evidence, 3.
Methods: NHL players undergoing ACL reconstruction were evaluated. All demographic data were analyzed. Matched controls
were selected from the NHL during the same years as those undergoing ACL reconstruction. The ‘‘index year’’ (relative to the
number of years of experience in the NHL) in controls was the same as the year that cases underwent ACL reconstruction. RTS and
performance in the NHL were analyzed and compared between cases and controls. Student t tests were performed for analysis of
within- and between-group variables. Bonferroni correction was used in the setting of multiple comparisons.
Results: A total of 36 players (37 knees) meeting the inclusion criteria underwent ACL reconstruction while in the NHL. Thirty-five
players were able to RTS in the NHL (97%), and 1 player returned to the international Kontinental Hockey League. Of the players who
RTS in the NHL, 100% were able to RTS the season after ACL reconstruction (mean, 7.8 ± 2.4 months). Length of career in the NHL
after ACL reconstruction was 4.47 ± 3.3 years. The revision rate was 2.5%. There were significantly more cases playing in the NHL at 3
(P ¼ .027) and 4 (P ¼ .029) years following surgery compared with controls (index year). After ACL reconstruction, player performance
was not significantly different from preinjury performance. Following ACL reconstruction (or index year in controls), cases played
significantly more minutes, took more shots, had better shooting percentages, and scored more goals and points than did controls
(P < .01 for all). Control players did not significantly outperform cases after ACL reconstruction in any performance measure.
Conclusion: There is a high RTS rate in the NHL following ACL reconstruction. All players who RTS did so the season following
surgery. Performance following ACL reconstruction was not significantly different from preinjury. Cases performed better than did
controls in several performance measures. Controls did not outperform cases in any measured performance variable.
Keywords: anterior cruciate ligament; National Hockey League; return to sport; tear; knee injury
†
Address correspondence to Joshua D. Harris, MD, 6550 Fannin
Street, Smith Tower, Suite 2600, Houston, TX 77030, USA (e-mail:
[email protected]).
*Midwest Orthopaedics at Rush, Rush University Medical Center,
Chicago, Illinois, USA.
One or more of the authors has declared the following potential conflict of
interest or source of funding: B.J.C. is a consultant for Zimmer, Arthrex, Carticept, Biomimetic, Allosource, and DePuy; receives speaking fees from Genzyme; receives royalties from Arthex, DJO, and Elsevier; and receives research
funding from Regentis, Arthrex, Smith & Nephew, DJO, Zimmer, DePuy, and
Johnson & Johnson. B.R.B. receives publishing royalties from Slack Inc. N.N.V.
is a consultant for Arthrex and Smith & Nephew; receives speaking fees from
Arthrosurface; receives royalties from Smith & Nephew, Vindico MedicalOrthpedics Hyperguide, and Arthroscopy; and holds stock in Omeros.
Anterior cruciate ligament (ACL) tears are one of the most
common injuries in both contact and noncontact sports.5
Although the incidence of ACL tears in football and basketball players has been well identified,14 there have been no
studies on the incidence of ACL tears in hockey players at
any level. There is currently no reported incidence of ACL
tears in athletes playing for the National Hockey League
(NHL) in North America. It is estimated that there will be
up to 200,000 ACL tears annually in the United States,3
more than half of which will be reconstructed surgically.7
ACL reconstruction is the standard of care in young athletes.
Although many studies report a high success rate following an ACL reconstruction,9 there are no data concerning
NHL players and their return to sport (RTS) after ACL tear.
The Orthopaedic Journal of Sports Medicine, 2(9), 2325967114548831
DOI: 10.1177/2325967114548831
ª The Author(s) 2014
This open-access article is published and distributed under the Creative Commons Attribution - NonCommercial - No Derivatives License (http://creativecommons.org/
licenses/by-nc-nd/3.0/), which permits the noncommercial use, distribution, and reproduction of the article in any medium, provided the original author and source are
credited. You may not alter, transform, or build upon this article without the permission of the Author(s). For reprints and permission queries, please visit SAGE’s Web site
at http://www.sagepub.com/journalsPermissions.nav.
1
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2
Erickson et al
The Orthopaedic Journal of Sports Medicine
NHL ACL tears
(N = 39 players; 40 knees)
Primary NHL ACL tears
(n = 36 players; 37 knees)
Excluded: <12 months follow-up aer ACL
reconstrucon (n = 3 players; 3 knees)
Primary NHL ACL tears
(n = 36 players; 37 knees)
Excluded: concomitant injuries
(n = 0 players, 0 knees)
NHL ACL tears
(N = 36 players, 37 knees)
Unable to return to NHL
(n = 1 player; 1 knee)
Returned to NHL
(n = 35 players, 36 knees)
Played in internaonal hockey league
(n = 1 player; 1 knee)
Figure 1. Flowchart of selection process for inclusive National Hockey League (NHL) players. ACL, anterior cruciate ligament.
Harris et al8 found an 86% RTS rate in NBA players after
ACL reconstruction, while Erickson et al6 found a 77% RTS
rate in Major League Soccer (MLS) players after ACL reconstruction. However, Ardern et al2 performed a systematic
review of all athletes who underwent ACL reconstruction
and found that while 82% RTS, only 63% RTS at their preinjury level. McCullough et al10 found similar results in high
school– and college-level football players who underwent
ACL reconstruction, in that 63% and 69%, respectively, RTS,
while only 43% reported they were able to return to their
preinjury level. With approximately 690 active NHL players,
the popularity of the NHL has been growing over the past
several years. This is evidenced by record total revenue for
the NHL in each season from 2007 to 2011, with the highest
revenue to date, US$2.9 billion, in 2011.13
The primary purposes of this study were to determine (1)
RTS rate to the NHL following ACL reconstruction, (2) performance on RTS, and (3) the difference in RTS and performance between players who underwent ACL reconstruction
and controls. The authors hypothesized that NHL players who
sustained an ACL tear and underwent reconstruction will
have (1) a >90% RTS rate; (2) no statistically significant difference in in-game performance parameters; and (3) no difference
between age-, sex-, position-, and experience-matched control
players.
METHODS
Thirty-nine NHL players who tore their ACLs and underwent reconstructive surgery between 1990 and 2013 were
identified. These players were discovered through NHL team
websites, publicly available Internet-based injury reports,
player profiles/biographies, and press releases. This method
of player selection has been used in multiple publications in
high-level evidence orthopaedic journals.1,4,6,8,11,12 The
search was conducted by an orthopaedic surgery resident and
a board-eligible orthopaedic surgeon in sports medicine fellowship training. All players who met the inclusion criteria
were included in this study as it related to RTS rate. A player
was deemed to have RTS if he played in any NHL game after
surgery or if he is less than 12 months out from date of injury
but is expected to RTS. A player did not RTS if he failed to
meet any of the aforementioned criteria.
Only players who returned to the NHL and had played at
least 1 full season were included in the pre- and postinjury
in-game statistical analysis. After implementation of this
criterion, 35 individual players remained whose pre- and
postinjury in-game performance could be analyzed and
compared (Figure 1). Of these 35 players, 1 player tore his
reconstructed ACL 4 years after surgery and then returned
the season after revision ACL reconstruction. Players were
excluded if they tore both cruciate ligaments or if they tore
2 or more major knee ligaments (ACL, posterior cruciate
ligament, medial collateral ligament, and lateral collateral
ligament). No player was excluded based on concomitant
injuries. Therefore, the total number of ACL tears analyzed
in this portion of the study was 36.
Demographic data (age at injury, body mass index [BMI],
position, months from injury to return to play, side of injury,
period of the game in which the injury occurred, years played
before and after the injury, and whether the player returned
to the NHL the season after the injury) as well as average ingame performance data per season (games played, goals,
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The Orthopaedic Journal of Sports Medicine
ACL Reconstruction in NHL Players
3
TABLE 1
Comparison of Cases and Controls Before Anterior Cruciate Ligament Reconstruction (Index Year in Controls)a
Cases
Age, y
Experience in NHL, y
Body mass index, kg/m2
Games played per season, n
Goals per season, n
Assists per season, n
Points scored per season
þ/– goal differential per seasond
Penalty time per season, min
Even-strength goals per season, n
Power play goals per season, n
Short-handed goals per season, n
Shots per season, n
Shooting percentage per season, %
Time on ice per season, min
Time on ice per game, min
27.1
6.61
27.1
391
12.9
17.7
31.1
1.05
41.9
8.95
4.27
0.697
120
10.5
983
17.0
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
4.05
4.18
1.75
319
10.5
12.2
22.0
6.08
30.4
6.09
3.83
0.840
63.0
5.50
421
3.90
Controls
27.1 ±
6.61 ±
27.1 ±
364 ±
8.70 ±
12.8 ±
21.6 ±
–0.236 ±
40.7 ±
6.88 ±
2.41 ±
0.640 ±
91.4 ±
8.92 ±
861 ±
14.5 ±
1.55
4.20
1.19
276
8.70
11.3
20.0
6.62
29.9
5.96
2.67
1.58
58.8
3.84
371
4.27
P Valueb
.971
.999
.924
.696
.068
.081
.056
.415
.868
.167
.026
.854
.060
.187
.231
.021
95% CIc
–1.5 to
–2.2 to
–0.61 to
–113 to
–0.33 to
–0.62 to
–0.24 to
–1.9 to
–13 to
–0.89 to
0.23 to
–0.56 to
–1.2 to
–0.77 to
–79 to
0.38 to
1.5
2.2
0.68
168
8.8
10
19
4.4
15
5.0
3.5
0.68
59
3.9
323
4.5
Values are expressed as mean ± SD.
Paired-samples Student t test with Bonferroni correction (statistical significance, P < .01).
c
95% CI of the difference between cases and controls.
d
A measure of how the player’s team did when he was on the ice. If the player has a positive number, more goals were scored by his team
when he was on the ice than allowed; if he has a negative number, his team allowed more goals than they scored when he was on the ice.
a
b
assists, points, þ/– goal differential, penalty minutes, evenstrength goals, power play goals, short-handed goals, shots,
shooting percentage, total time on ice, and average time on ice
per game) were collected and analyzed. In-game performance
variables were analyzed as an average over the pre- and postinjury course of the players’ careers. In addition, in-game performance variables were analyzed separately in each of the
first 5 subsequent seasons the player returned to the NHL following the injury.
A control group was selected to compare the data with
the case (ACL reconstruction) group. Controls were
matched to cases based on sex, age, BMI, years of experience in the NHL, position, and all measured performance
variables (Table 1). ACL reconstruction occurred at a mean
of 6.61 ± 4.18 years into a player’s career. An ‘‘index year’’
was designated for controls, analogous to ACL reconstruction year in cases, as a matched reference year (relative
to years experience in NHL) to compare post-ACL reconstruction or post–index year performance. Hence, if a
player tore his ACL 4 years into his career, a control was
selected with an index year of 4 years into his career. Demographic data (BMI, age, years in the NHL) and in-game performance data were collected and analyzed over the course
of their careers before and after the index year (each season
analyzed individually and collectively).
Single-variable analyses for all continuous variables (performance measures) within groups were performed using
paired-sample Student t tests. One-sample KolmogorovSmirnov goodness-of-fit tests for Gaussian data distribution
were performed and confirmed normality of all data. Comparisons between case and control groups were made using Student t tests. Comparisons were made between cases and
controls for survival in the NHL, each individual parameter’s
overall mean (all years before and all years after ACL
reconstruction [or index year]), and each individual year
(up to 4 years) following ACL reconstruction (or index year
in controls). Bonferroni correction was used to determine significance in the setting of multiple comparisons. Twoproportion Z tests with equal variance and a ¼ 0.05 were used
to compare left- versus right-hand shooters and left- versus
right-side ACL tear distributions. All statistical analysis was
performed using PASW Statistics student version 18.0.0.
RESULTS
A total of 36 players (37 ACL tears) with ACL tears who
underwent reconstruction between 1990 and 2013 met the
inclusion criteria and were analyzed (Figure 1). Thirty-five
players (36 knees) were able to RTS in the NHL (97% rate
of RTS). However, the 1 player unable to return to NHL was
able to successfully return to professional international
hockey in the Kontinental Hockey League. Players returned
to the NHL at a mean of 7.8 ± 2.4 months following ACL tear.
Length of career in the NHL following ACL reconstruction
up to and including the 2012-2013 season was 4.47 ± 3.33
years. One player of 36 underwent revision ACL reconstruction. Nineteen of these players (53%) remained active in the
NHL. There were significantly more players in the NHL at
years 2 and 3 after ACL reconstruction (vs index year in controls) (Figure 2). Left-handed shooters made up 68% of cases
with ACL tears (P ¼ .002; Z ¼ 3.1), and 55% of ACL tears
occurred in the right knee (P ¼ .39; Z ¼ 0.86). ACL tears
by year are listed in Figure 3.
Prior to ACL reconstruction (or index year in controls),
players who tore their ACLs and controls had no statistically
significant differences in any demographic or performance
variable (Table 1). After ACL reconstruction, NHL players
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4
Erickson et al
The Orthopaedic Journal of Sports Medicine
40
35
35
35
35
ACL Reconstruction
Control
Number of Players
35
30
30
25
21
20
22
12
15
10
8
12
10
5
3
0
0
1
2
3
4
5
Years After ACL Reconstruction
Figure 2. Survival curve. There was a significant difference in
survival in the National Hockey League at years 2 (P ¼ .0273;
95% CI, 0.0258-0.4342; Z ¼ 2.21) and 3 (P ¼ .0293; 95% CI,
0.0262-0.4938; Z ¼ 2.18).
9
Number of ACL Tears
8
7
6
5
4
3
2
1
0
1985
1990
1995
2000
2005
2010
2015
Year
Figure 3. Anterior cruciate ligament (ACL) tears by year in
National Hockey League players.
who tore their ACLs performed significantly better (vs
controls) in mean goals and points per season, mean power
play and even-strength goals per season, and mean shots
and shooting percentage per season (Table 2). Compared
with preinjury, there were no significant differences in
any performance measure in players who underwent ACL
reconstruction (Table 3). Following the index year, controls played fewer games after their index season (Table 4).
In years 3 and 4 after ACL reconstruction in cases (or
index year in controls), the cases scored significantly more
goals and had significantly more points than controls.
DISCUSSION
The study hypotheses were confirmed, as there was a 97% rate
of RTS in NHL players, with no statistically significant difference in in-game performance parameters from preinjury to
postsurgery and improvement in several in-game performance measures compared with controls.
Two separate case-control studies performed at the
authors’ institution6,9 examined RTS and performance in
64 National Basketball Association (NBA) players and 52
MLS players. Those studies demonstrated a lower return
to high-level sports (86% to the NBA and all but 1 player
[98%] returned to any level of competitive professional
basketball, while there was a 77% rate of RTS to MLS)
than the current study (97% RTS in NHL). It is unclear
exactly what factors play a role in the ability or inability
of a professional athlete to RTS after an ACL reconstruction. The demands of each sport, as well as the forces seen
by the knees, vary, and because of this, future kinetic and
kinematic studies comparing the stresses placed on the
knee during various professional sports are necessary to
determine if there is a way to improve the RTS rate of
these athletes.
The current study demonstrated a revision rate of only
2.5% (1/37 ACL reconstructions needed to be revised),
while the NBA and MLS studies demonstrated revision
rates of 3.1% and 10%, respectively. This is an interesting finding, as many ACL tears in NHL athletes are
likely contact injuries because there is no significant
jumping involved in hockey and players cleats do not get
caught in the ground (in MLS and the NBA, these injuries are often noncontact). This mechanism of injury may
predispose these athletes to higher revision rates on
RTS, as ACL reconstructions can more reliably withstand contact injuries than noncontact injuries. This
begs the question of whether improved proprioceptive
training could lead to a decrease in these revision rates
in noncontact injuries of MLS and the NBA.
The NBA study showed a significant decline in games
played per season versus controls following ACL reconstruction (or index year in controls), while the current
study showed no difference in games played between cases
and controls. The MLS study, like the current study, did not
demonstrate a decline in any in-game performance parameter. Thus, among players in the NBA, MLS, and NHL,
those who sustain an ACL tear in the NHL perform the best
and have the highest RTS rate after reconstruction. This is
a very significant finding for current and future professional NHL players, as an ACL tear does not signify the end
of a player’s career, and players can expect to return to
their preinjury level of competition. Interestingly, there
seemed to be a trend toward an increase in the number of
ACL tears in NHL players between 2007 and 2010,
although this did not reach statistical significance. As there
were no rule changes or other explanations that could have
accounted for this spike, it is likely due to chance.
Unlike ACL tears in elite football, soccer, and basketball
players, which have been extensively studied,6,9,10 the
authors could find no studies to date that have looked at the
RTS rate or the performance on RTS in the NHL or other
elite-level hockey players. Furthermore, there have not
been any studies that evaluated the risk of ACL tear in
NHL players. The current study identified 40 ACL tears
over a 13-year period, giving an incidence of roughly 3 ACL
tears per year in NHL players.
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The Orthopaedic Journal of Sports Medicine
ACL Reconstruction in NHL Players
5
TABLE 2
Comparison of Cases and Controls After Anterior Cruciate Ligament Reconstruction (Index Year in Controls)a
Cases
Games played per season, n
Goals per season, n
Assists per season, n
Points scored per season
þ/– goal differential per seasond
Penalty time per season, min
Even-strength goals per season, n
Power play goals per season, n
Short-handed goals per season, n
Shots per season, n
Shooting percentage per season, %
Time on ice per season, min
Time on ice per game, min
256 ±
13.9 ±
18.1 ±
32.5 ±
–0.265 ±
41.0 ±
10.3 ±
4.43 ±
0.487 ±
138 ±
9.94 ±
1172 ±
17.5 ±
234
13.2
12.6
25.1
8.75
29.7
8.84
4.23
0.789
75.5
4.64
437
4.11
Controls
217 ±
6.82 ±
11.7 ±
18.3 ±
–0.815 ±
36.6 ±
5.20 ±
1.84 ±
0.235 ±
87.1 ±
6.96 ±
860 ±
14.6 ±
142
7.00
9.47
15.7
4.59
24.8
4.82
2.14
0.308
52.0
3.35
359
4.37
P Valueb
.473
.009
.035
.009
.761
.550
.007
.004
.104
.007
.007
.007
.014
95% CIc
–68 to
1.8 to
0.47 to
3.7 to
–3.1 to
–10 to
1.5 to
.86 to
–0.05 to
14 to
0.84 to
89 to
0.63 to
145
12
12
25
4.2
19
8.8
4.3
0.56
87
5.1
535
5.3
Values are expressed as mean ± SD. Values in bold and italics indicate statistically significant differences between groups.
Paired-samples Student t test with Bonferroni correction (statistical significance, P < .01).
c
95% CI of the difference between cases and controls.
d
A measure of how the player’s team did when he was on the ice. If the player has a positive number, more goals were scored by his team
when he was on the ice than allowed; if he has a negative number, his team allowed more goals than they scored when he was on the ice.
a
b
TABLE 3
Performance Comparison Before and After Anterior Cruciate Ligament Reconstruction (Cases)a
Before
Goals per season, n
Assists per season, n
Points scored per season
þ/– goal differential per seasond
Penalty time per season, min
Even-strength goals per season, n
Power play goals per season, n
Short-handed goals per season, n
Shots per season, n
Shooting percentage per season, %
Time on ice per season, min
Time on ice per game, min
12.9 ±
17.7 ±
31.1 ±
1.05 ±
41.9 ±
8.95 ±
4.27 ±
0.697 ±
120 ±
10.5 ±
983 ±
17.0 ±
10.5
12.2
22.0
6.08
30.4
6.09
3.83
0.840
63.0
5.50
421
3.90
After
13.9 ±
18.1 ±
32.5 ±
–0.265 ±
41.0 ±
10.3 ±
4.43 ±
0.487 ±
138 ±
9.94 ±
1172 ±
17.5 ±
13.2
12.6
25.1
8.75
29.7
8.84
4.23
0.789
75.5
4.64
437
4.11
P Valueb
95% CIc
.733
.904
.805
.482
.899
.459
.875
.298
.300
.667
.088
.599
–6.6 to 4.6
–6.2 to 5.5
–12 to 9.7
–2.4 to 5.0
–13 to 15
–5.1 to 2.3
–2.1 to 1.8
–0.19 to 0.61
–52 to 16
–2.0 to 3.0
–407 to 29
–2.6 to 1.5
Values are expressed as mean ± SD.
Paired-samples Student t test with Bonferroni correction (statistical significance, P < .01).
c
95% CI of the difference between before and after values.
d
A measure of how the player’s team did when he was on the ice. If the player has a positive number, more goals were scored by his team
when he was on the ice than allowed; if he has a negative number, his team allowed more goals than they scored when he was on the ice.
a
b
The NHL players reviewed in this study who underwent
ACL reconstruction did not see either a decline or improvement in their performance after surgery. This is a reassuring
finding as surgeons would not expect to find an improvement
in performance after surgery but rather hope to prevent a
decline in performance. Also, despite the fact that the NHL
players who underwent ACL reconstruction performed better than the control group in some performance variables
after surgery, this statistic may be construed as players who
have ACL reconstruction do better than those who do not.
The players who had ACL reconstruction may have been
more elite athletes to begin with and had not had a chance
to fully develop prior to their injury. Also, in their recovery
period after surgery, they are spared the rigors of playing
in game situations, and so when they did return from their
injury, their bodies were rested and primed for competition.
A unique finding in the current investigation is that a
greater number (68%) of ACL tears in NHL players
occurred in left-handed shooters (P ¼ .002), while the
number of tears in right versus left knees did not significantly differ (55% vs 45%; P ¼ .39). In the previously
reported NBA player case-control study, the side distribution (right vs left) was nearly identical to the current
study (51% vs 49%, respectively), while that of the MLS
was significantly different, with 68% of tears occurring
in the left knee. The exact etiology of this significant
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6
Erickson et al
The Orthopaedic Journal of Sports Medicine
TABLE 4
Performance Comparison Before and After Index Season (Controls)a
Before
Mean games played per season
Goals per season, n
Assists per season, n
Points scored per season
þ/– goal differential per seasond
Penalty time per season, min
Even-strength goals per season, n
Power play goals per season, n
Short-handed goals per season, n
Shots per season, n
Shooting percentage per season, %
Time on ice per season, min
Time on ice per game, min
364
8.70
12.8
21.6
–0.236
40.7
6.88
2.41
0.640
91.4
8.92
861
14.5
±
±
±
±
±
±
±
±
±
±
±
±
±
276
8.70
11.3
19.6
6.62
29.9
5.96
2.67
1.58
58.8
3.84
371
4.27
After
217 ±
6.82 ±
11.7 ±
18.3 ±
–0.815 ±
36.6 ±
5.20 ±
1.84 ±
0.235 ±
87.1 ±
6.96 ±
860 ±
14.6 ±
142
7.00
9.47
15.7
4.59
24.8
4.82
2.14
0.308
52.0
3.35
359
4.37
P Valueb
.009
.374
.673
.497
.718
.577
.269
.400
.231
.782
.053
.995
.966
95% CIc
38
–2.3
–4.3
–6.2
–2.6
–10
–1.3
–0.78
–0.26
–26
–0.03
–200
–2.4
to 255
to 6.1
to 6.7
to 13
to 3.8
to 19
to 4.7
to 1.9
to 1.1
to 35
to 3.9
to 201
to 2.3
Values are expressed as mean ± SD. Values in bold and italics indicate statistically significant differences between groups.
Paired-samples Student t test with Bonferroni correction (statistical significance, P < .01).
c
95% CI of the difference between before and after values.
d
A measure of how the player’s team did when he was on the ice. If the player has a positive number, more goals were scored by his team
when he was on the ice than allowed; if he has a negative number, his team allowed more goals than they scored when he was on the ice.
a
b
increase in tears in left-handed shooters is not clear at
this time. It may take origin in shooting mechanics, but
without a biomechanical study to verify this, this is simply an observation.
Limitations
The strengths of this study include its case-matched control
comparative design and use of sport-specific performance
parameters. Limitations include the use of publicly available data, which can be subject to observer bias because
of anticipated media and/or public scrutiny. There is the
possibility that some cases were missed and that these
players did not do well after their ACL reconstructions,
thereby leading to a falsely high RTS rate. However, the
opposite is also true, in which players who had a successful
ACL reconstruction were missed but went on to play well,
which would have falsely lowered the RTS rate. Nevertheless, this method of subject selection has been utilized in
multiple high–evidence level studies in sports medicine
journals.1,4,6,9,11,12 Another limitation was that no subject
patient-reported or clinician-measured outcomes were
available; this includes general health (eg, Short Form–
36) and joint-specific (eg, Knee Society Score [KSS]).
Furthermore, postinjury patient satisfaction and personal
perception of knee pain, function, and stability versus preinjury were unable to be assessed. These factors may influence RTS performance. Surgical technique information was
unobtainable from publicly available sources, although it
can be inferred by the treating surgeon based on preferences expressed in publications and/or presentations.
Because of the high-profile nature of these athletes, they
are unable to be easily contacted to assess these outcome
measures. Additionally, the rehabilitation program utilized postoperatively was unavailable. Even though only
1 player was unable to return to play in the NHL following
ACL reconstruction, the inability to return cannot solely
be attributed to ACL injury and surgery, as other confounders inevitably coexist. Furthermore, although all
performance-based measures were used to compare preand postoperative outcomes and between cases and controls, other intangibles (team leadership, teammate motivation, etc) cannot be assessed for relationships.
CONCLUSION
There is a high RTS rate in the NHL after ACL reconstruction. All players who RTS did so the season following surgery. Performance following ACL reconstruction was not
significantly different from preinjury. Cases performed better than controls in several performance measures.
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